Take a look of this two guides.
As you say, that CPU have two ways for overclock. Multiplier and FSB, I recommend you use the multiplier. You also will need a better cooler.
1- Multiplier: You only change the CPU frequency, keep in mind that the formula is this: reference clock (200MHz) x CPU multiplier (x17)= = CPU frequency (3400MHz). You will need add voltage to the CPU in some points for get it stable, but don't go above 1.5V and 55ÂºC or you can have problems.
2- FSB: With this you also can change the CPU frequency, but the FSB is linked with the HT, NB and DRAM frequency, so, you get more troubles for get all the rig stable that only with multiplier.
Only the BE CPUs like your can be overclocked using multiplier